Our overall hypothesis is that oxytocin is an important contributor to neonatal cerebrovascular control especially following pharmacological and pathological impairment of the prostaglandin synthetic system. Our hypothesis is supported by several interconnecting findings in newborn pigs: 1) Oxytocin levels increase in cerebrospinal fluid (CSF) and plasma to vasoactive levels during stressful conditions such as asphyxia, increased intracranial pressure, and osmotic stress; 2) Indomethacin pretreatment reverses cerebral arteriolar responses to oxytocin from dilation to potent constriction; 3) Indomethacin pretreatment alters oxytocinergic vascular responses in both pial arterioles and basilar artery; and 4) Pathological conditions such as global ischemia and the presence of subarachnoid blood cause impairment of prostaglandin-dependent responses in the cerebral circulation. Based upon our findings and those in the literature, we propose the following specific hypotheses: 1. Cerebral resistance vessels are exposed to vasoactive levels of oxytocin via CSF and plasma; 2. Prostaglandin synthetic capabilities of cerebral tissues and/or vessels are an important determinant of cerebrovascular responses to oxytocin; and 3. Impairment of the prostaglandin system by pathological stimuli results in altered responsiveness of cerebral arteries and arterioles to oxytocin. To test these hypotheses, three specific aims will be addressed using newborn pigs: 1. CHARACTERIZATION OF OXYTOCINERGIC EFFECTS ON CEREBROVASCULAR HEMODYNAMICS; 2. INVESTIGATION OF THE CONTRIBUTION OF PROSTAGLANDINS TO CEREBROVASCULAR RESPONSES TO OXYTOCIN; and 3. DETERMINATION OF CEREBROVASCULAR EFFECTS OF OXYTOCIN FOLLOWING PATHOLOGICAL ALTERATIONS IN THE PROSTAGLANDIN SYSTEM. We will use several complimentary methods for studying cerebrovascular responses, including the closed cranial window and intravital microscopy for characterization of individual arteries and arterioles in vivo, radioactive microspheres for determination of total and regional cerebral blood flow, microvascular measurement of blood pressure for determination of segmental resistance, and in vitro approaches for examining vascular responses in isolation. In addition, we will determine oxytocin and prostaglandin levels by radioimmunoassay. This investigation will explore control mechanisms in neonatal animals during normal and pathological conditions. We hope that our findings will be of clinical relevance and lead to therapies that improve outcome in stressed babies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL050587-01A2
Application #
2226835
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1994-12-01
Project End
1997-11-30
Budget Start
1994-12-01
Budget End
1995-11-30
Support Year
1
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Wake Forest University Health Sciences
Department
Physiology
Type
Schools of Medicine
DUNS #
041418799
City
Winston-Salem
State
NC
Country
United States
Zip Code
27106
Katakam, Prasad V G; Jordan, James E; Snipes, James A et al. (2007) Myocardial preconditioning against ischemia-reperfusion injury is abolished in Zucker obese rats with insulin resistance. Am J Physiol Regul Integr Comp Physiol 292:R920-6
Mayanagi, Keita; Gaspar, Tamas; Katakam, Prasad V G et al. (2007) The mitochondrial K(ATP) channel opener BMS-191095 reduces neuronal damage after transient focal cerebral ischemia in rats. J Cereb Blood Flow Metab 27:348-55
Csordas, Attila; Pankotai, Eszter; Snipes, James A et al. (2007) Human heart mitochondria do not produce physiologically relevant quantities of nitric oxide. Life Sci 80:633-7
Horvath, Eszter M; Lacza, Zsombor; Csordas, Attila et al. (2006) Graft derived cells with double nuclei in the penumbral region of experimental brain trauma. Neurosci Lett 396:182-6
Erdos, Benedek; Snipes, James A; Tulbert, Christina D et al. (2006) Rosuvastatin improves cerebrovascular function in Zucker obese rats by inhibiting NAD(P)H oxidase-dependent superoxide production. Am J Physiol Heart Circ Physiol 290:H1264-70
Lacza, Zsombor; Kozlov, Andrey V; Pankotai, Eszter et al. (2006) Mitochondria produce reactive nitrogen species via an arginine-independent pathway. Free Radic Res 40:369-78
Katakam, Prasad V G; Snipes, James A; Tulbert, Christina D et al. (2006) Impaired endothelin-induced vasoconstriction in coronary arteries of Zucker obese rats is associated with uncoupling of [Ca2+]i signaling. Am J Physiol Regul Integr Comp Physiol 290:R145-53
Lacza, Zsombor; W Busija, David (2006) Urotensin-II is a nitric oxide-dependent vasodilator in the pial arteries of the newborn pig. Life Sci 78:2763-6
Busija, David W; Miller, Allison W; Katakam, Prasad et al. (2006) Adverse effects of reactive oxygen species on vascular reactivity in insulin resistance. Antioxid Redox Signal 8:1131-40
Lacza, Zsombor; Pankotai, Eszter; Csordas, Attila et al. (2006) Mitochondrial NO and reactive nitrogen species production: does mtNOS exist? Nitric Oxide 14:162-8

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